Issue |
Metall. Res. Technol.
Volume 120, Number 1, 2023
|
|
---|---|---|
Article Number | 114 | |
Number of page(s) | 13 | |
DOI | https://doi.org/10.1051/metal/2023010 | |
Published online | 15 February 2023 |
Original Article
Investigation on the pitting corrosion properties of welded joints of bimetal composite pipe
1
School of New Energy and Materials, Southwest Petroleum University, Chengdu 610500, China
2
Sichuan Petroleum Engineering Construction Co. Ltd, Chengdu 610000, China
3
School of Engineering, Southwest Petroleum University, Chengdu 610500, China
* e-mail: 380056676@qq.com
Received:
26
April
2022
Accepted:
9
January
2023
A bimetallic composite pipe butt joint was prepared by automatic gas tungsten arc welding (GTAW). The microstructure and pitting properties of the joint were investigated. The results show that the microstructure of the joint is columnar crystal, columnar dendrite, and equiaxial crystal. Mo, Nb, and Cr segregate in joint and form Laves and NbC precipitates in the interdendritic. The heat-affected zone (HAZ) becomes the preferred region for pitting due to recrystallization behavior and large and continuous Laves, this was demonstrated by both immersion corrosion and electrochemical experiments. To better understand the pitting behavior of the joint, this study discusses the mechanism of passive film rupture and pitting development, and uses electrolytic corrosion by Nital to simulate the morphology of the initial corrosion pits around the Laves phase.
Key words: bimetal composite pipe / Inconel 625 / GTAW / Laves / pitting corrosion
© EDP Sciences, 2023
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